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If there's one thing we should learn from this election — but probably won't — it's that our ability to understand fast-moving events and foresee where they are going is far more limited than we believe. I'll try to swallow that bitter medicine.

What follows, then, is not a prediction. It is merely a future that is possible. And undesirable.

There is ample evidence that in politics and ideology, Canadians are overwhelmingly centrist. In public policy, there is widespread agreement. Even in areas that are ostensibly controversial, like immigration and multiculturalism, most people agree on basics such as "immigration strengthens Canada" and "cultural diversity is good."

There are disagreements, of course. But they're usually about details and fine-tuning, not fundamentals.

Canadian politics has reflected this centrism fairly well. All the main political parties support immigration and multiculturalism. All the parties support universal public health care. All the parties support action on climate change. And so on down the list.

The parties' priorities vary and there are meaningful disagreements on many issues, but it's a mistake to focus solely on the differences. What they share in common is far greater.

Look at the debate about corporate income tax rates. The Conservatives want to push ahead with cuts that will take the rate from 16.5 per cent to 15 per cent. The Liberals promised to restore the 18 per cent rate that was in place before this year. The NDP wanted it to go to 19.5 per cent.

These differences are not insignificant, but in a wider perspective, they're clearly modest — and all parties, even the NDP, agreed with the underlying idea that keeping corporate tax rates low is a good idea because it gives Canada an economic advantage.

Canadian politics has never been extreme but the trend toward centrism and consensus has been accelerating at least since the mid-1990s, when the Reform party's rough edges wore off and the Liberals became more fiscally conservative than the Progressive Conservatives who preceded them.

Personalities and partisan nastiness often obscure the trend, but it's undeniable. Remarkably few of Stephen Harper's policies of the last five years could not have come from a Liberal government. And Jack Layton may look like V.I. Lenin but his NDP is only a few degrees to the left of dead centre.

But all this was before the collapse of the Liberal party.

Of course we don't know if the Liberals will stay down. Popular support levels for all three parties were flat as Saskatchewan for years prior to the election and then, in two weeks, the NDP and Liberals reversed positions.

What happened? It wasn't just politics.

I think we need to look to the social psychology that explains trends, fashions, and manias. And we need to consider the possibility that this polarity flip will vanish like the Rubik's Cube craze. I have no idea how likely that is. But the probability will surely rise if the NDP's new caucus — overflowing with hilariously unqualified neophytes — turns into a circus.

But for the sake of argument, let's say this is permanent and the erstwhile "Natural Governing Party" is now the third wheel of Canadian politics. What comes next?

Inevitably, there will be talk of merging the NDP and the Liberals. Michael Ignatieff has argued compellingly that the two parties come from very different political traditions and those who talk of uniting "the left" don't understand what the Liberals are. But Ignatieff's word won't carry much weight with anyone.

A merger is possible. And Canadian politics could become a dichotomous choice of left or right.

But if the Liberals remain a mere rump, that may happen even without a merger. British experience shows this.

By 1924, the once-mighty British Liberal party had been reduced to a distant third. It didn't vanish. But it was never again the centre of political gravity and the Conservatives and Labour became the yin and yang of British politics.

Something similar is quite possible here. In a matchup between the Conservatives and NDP — particularly at a time when voter turnout is appallingly low — the electoral math may show that moving to the centre to grab some of the dwindling number of Liberal voters is no longer the smartest option.

The more effective strategy may be to identify, engage, and energize the party's base.

That's done two ways. One, demonize the opposition. Portray them as extreme. Call them a threat to all the base holds dear. Two, move away from the centre: Conservatives to the right, NDP to the left.

If that were to happen, Canadian politics would become increasingly polarized and nasty. And Canadians would increasingly be asked to choose between two options which do not reflect the centrist views of the population as a whole.

If that sounds impossible, look south. A mountain of research shows that Americans are overwhelmingly clustered in the political middle. Very simply, most Americans are moderate centrists. And yet, American politics is divided and polarized like never before because, in part, the political dynamics reward division and polarization.

Is it unthinkable that Canada may go in this direction? Perhaps.

But remember it was not so long ago that what happened Monday night was unthinkable.